Systems for assisting in many objects up and down stairs have been devised, improved, digressed and modified for the last century. The majority of these systems involve a cart-like device that travels up and down the stairs. The present invention is the opposite of this concept.
The following patents with a short description of each are a result of a fairly complete and extensive patentability search completed on Sep. 8, 2008. No representation is made with respect to patents issued after that date nor is the exhaustive nature of the search represented to the examiner.
U.S. Pat. No. 2,990,929 discloses a wheel or roller used in a package conveyor.
U.S. Pat. No. 6,042,061 discloses a roller rung having a number of roller drums for a cable bed to draw and lay a cable (or pipe) on the cable bed.
U.S. Pat. No. 5,048,661 discloses a roller conveyor.
U.S. Pat. No. 2,325,762 discloses a boat leading attachment for automobiles that provides rollers to assist in loading a boat on position above a car.
U.S. Pat. Nos. 777,594, 617,968, 2,517,112, 1,411,044, 2,451,620, and 1,337,356 disclose a roller support for rolling and conveying a piece of wood.
U.S. Pat. No. 2,405,810 discloses a boat handling and launching apparatus that uses adjustable rollers to convey the boat.
U.S. Pat. No. 2,405,810 discloses dock rollers for boats to bring the boats from the water onto the dock.
U.S. Pat. No. 4,706,983 titled “Assembly for Towing a Boat” discloses a pair of channel members mounted on the transom of a boat.
U.S. Pat. No. 4,327,933 titled “Sailboat Carrier” discloses a single-wheeled dolly system that has a frame with clips which attach to the rungs of a ladder.
U.S. Pat. No. 3,575,439 titled “Load Conveying Cart” discloses a single wheel mounted in the center of an axle running the width of the attached cart.
U.S. Pat. No. 7,387,306 titled “Dolly” discloses a two-wheeled dolly with carrying frame with scoop.
Existing “load bearers” or “transport systems” consist primarily of dollies (U.S. Pat. No. 7,387,306), lifts, load carriers (U.S. Pat. Nos. 3,575,439, 4,327,933), stair tow systems. They are generally of the two wheeled or more varieties. Single-wheeled devices have been proposed for such purposes as carrying boats, ladders, and game animals (cart). Those devices used as boat carriers need to be used in pairs as they are attached to the boat or have cradles in which the boat is placed. However, a ladder caddy (U.S. Pat. No. 5,727,799) is a single-wheeled unit with a frame and clips that attach to the ladder rungs. Load conveying carts also use a single wheel that is mounted in the center of the axle which runs the full width of an accompanying cart.
The use of rollers to convey an item is well known in the art as shown by U.S. Pat. Nos. 2,405,810, 777,584, 617,968, 6,042,061 and 2,990,929. The U.S. Pat. Nos. 6,042,061 and 2,990,929 each disclose a roller in a frame. The rollers could be used to convey items up steps if the frames were different.